Inspection Procedure

WARNING: This page is about a different car, the 2008 Lexus IS 350. However, it is still accessible from the selected car via links, so may be relevant.

HINT:

If any of DTCs P0115, P0117, P0118 or P0125 are set simultaneously with DTC P0116, the ECT sensor may have an open or a short circuit. Troubleshoot those DTCs first.
Read freeze frame data using Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction (See FREEZE FRAME DATA ).

CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0116)

Connect Techstream to the DLC3.
Turn the engine switch on (IG).
Turn the tester on.
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

Read the DTC.

Result

RESULT REFERENCE CHART

Display (DTC output)	Proceed to
P0116	A
P0116 and other DTCs	B

B: GO TO DTC CHART

A: Go to next step

INSPECT THERMOSTAT
1. Remove the thermostat (See REMOVAL ).
2. Check the valve opening temperature of the thermostat.
  Standard:
  
  80 to 84°C (176 to 183°F)
  
  HINT:
  
  In addition to the above check, confirm that the valve is completely closed when the temperature is below the standard.
3. Reinstall the thermostat (See INSTALLATION ).
NG: REPLACE THERMOSTAT

OK: REPLACE ENGINE COOLANT TEMPERATURE SENSOR